The subject application relates to drop ejection, and in particular to pattern ejection of a mist of very small droplets from capillary waves.
An example of a drop ejector which operates to eject droplets by controlling capillary wave action is set forth in U.S. Pat. No. 5,194,880, titled, “Multi-Electrode, Focused Capillary Wave Energy Generator”, to Elrod et al., issued Mar. 16, 1993, which discloses a capillary wave printer that can generate a ripple wave at the top of a fluid container. An electro-acoustic transducer positioned at the bottom of a fluid container generates a ripple wave, and the wave propagates through the fluid reservoir, resulting in a disturbance of the fluid reservoir. Consequently, the top of the fluid reservoir can begin to emit droplets of fluid due to the vibrations imparted by the piezoelectric pushers.
However, Elrod et al. is directed to the formation of complex high resolution images and requires employing costly complex switching and imaging electronics and sophisticated operations to control the capillary waves for individual drop ejection and placement. Thus, such devices do not lend themselves to industrial uses which would have need for ejectors able to generate simple patterns by use of a low cost printhead design, which permit for simplified control operations.